/* Child process for syn-rw.
   Reads from a file created by our parent process, which is
   growing it.  We loop until we've read the whole file
   successfully.  Many iterations through the loop will return 0
   bytes, because the file has not grown in the meantime.  That
   is, we are "busy waiting" for the file to grow.
   (This test could be improved by adding a "yield" system call
   and calling yield whenever we receive a 0-byte read.) */

#include <random.h>
#include <stdlib.h>
#include <syscall.h>
#include "tests/filesys/extended/syn-rw.h"
#include "tests/lib.h"

static char buf1[BUF_SIZE];
static char buf2[BUF_SIZE];

int main(int argc, const char *argv[])
{
    int child_idx;
    int fd;
    size_t ofs;

    test_name = "child-syn-rw";
    quiet = true;

    CHECK(argc == 2, "argc must be 2, actually %d", argc);
    child_idx = atoi(argv[1]);

    random_init(0);
    random_bytes(buf1, sizeof buf1);

    CHECK((fd = open(file_name)) > 1, "open \"%s\"", file_name);
    ofs = 0;
    while (ofs < sizeof buf2)
    {
        int bytes_read = read(fd, buf2 + ofs, sizeof buf2 - ofs);
        CHECK(bytes_read >= -1 && bytes_read <= (int)(sizeof buf2 - ofs),
              "%zu-byte read on \"%s\" returned invalid value of %d",
              sizeof buf2 - ofs, file_name, bytes_read);
        if (bytes_read > 0)
        {
            compare_bytes(buf2 + ofs, buf1 + ofs, bytes_read, ofs, file_name);
            ofs += bytes_read;
        }
    }
    close(fd);

    return child_idx;
}
